Evaluation the role of cholinergic system in glucocorticoids-induced enhancement of memory consolidation in mice

Objectives: Many evidence indicated that glucocorticoids enhanced memory consolidation in a variety of tasks, but the underlying mechanism(s) are not clear. The aim of this study was to determine the role of cholinergic system in glucocorticoids-induced enhancement of memory consolidation in mice. Methods: In this experimental study were performed on 100 male albino mice (about 30 g). The animals were trained in an inhibitory avoidance task (0.5 mA shock for 3 seconds). In Experiment 1, effects of corticosterone were determined. Immediately after training, the animals received of vehicle or corticosterone (0.3 mg/kg). In Experiments 2 and 3, effects of corticosterone were examined in the presence of absence of atropine, a blocker of muscarinic cholinergic receptors, (0.5 and 2 mg/kg) or Mecamylamine, a blocker of nicotinic cholinergic receptors, (0.5 and 2 mg/kg), respectively. In all experiments, memory retention tested 48 hr later. Results: Results indicated that Corticosterone enhanced memory consolidation significantly (P<0.01). Blockade of muscarinic cholinergic receptors by atropine suppressed the glucocorticoids response dose-dependently. Blockade of nicotinic cholinergic receptors by Mecamylamine did not change the glucocorticoids response. Also both blockers alone did not change memory consolidation as compared with control group. Conclusion: Finding above showed that the memory enhancing effects of corticosterone, at least in part; may mediate via muscarinic cholinergic receptors.